Differences in hepatitis C virus quasispecies composition between liver, peripheral blood mononuclear cells and plasma.

Abstract

Hepatitis C virus (HCV) exists in vivo as a highly variable mixture of closely related genomes (quasispecies), but the pathogenetic significance of such heterogeneity is still largely unknown. To investigate this issue, we compared the composition of HCV quasispecies found in the liver, peripheral blood mononuclear cells (PBMC) and plasma of ten patients by single-strand conformation polymorphism analysis of the E2/NS1 region and sequencing of the variants detected. We found considerable quasispecies differences between the liver and PBMC in all the patients, involving variant numbers, relative quantities and relative electrophoretic mobilities, but no apparent tissue-specific trend. Genome variants present in the liver and/or PBMC were not detected in the corresponding plasma samples, while certain HCV variants were present only in plasma. No dominant amino acids or amino acid pattern characteristic of variants present solely in the PBMC were detected in the E2/NS1 region sequenced.Hepatitis C virus (HCV) exists within infected hosts as a variably complex system of related genomes (quasispecies) generated by the limited fidelity of RNA replication. Recent evidence has shown that quasispecies composition exhibits extensive variation within individual isolates (Okada et al., 1992) and can vary spontaneously both over time (Kao et al., 1995) and with liver disease progression . In addition, the extent of HCV quasispecies diversity has been reported to be predictive of responsiveness to interferon treatment (Moribe et al., 1995) and to decrease markedly

Quasispecies of hepatitis C virus in serum and in three different parts of the liver of patients with chronic hepatitis

“…The quasispecies nature of HCV seemed to relate to the pathogenesis of persistent infection 8,9,22,23 and to the effectiveness of interferon therapy, 5,10,11 but its pathogenetic significance is still unknown. Although, hepatocytes are thought to be the principal site of HCV replication, there have only been a few studies on the quasispecies nature of liver [12][13][14]24 and the results of these studies were conflicting. Sakamoto et al reported no difference in diversity of HCV quasispecies between plasma and liver from data obtained by single-strand conformation polymorphism.…”

Extrahepatic replication of HCV: Insights into clinical manifestations and biological consequences

“…[79][80][81] While some of these data should be viewed cautiously, as a variety of techniques were utilized and a limited number of samples [82][83][84] Interestingly, sequence analysis has subsequently revealed that certain viral variants may be selected for growth in extrahepatic cell types, implying that HCV diversity directly impacts cell tropism. 85,86 Furthermore, several studies have described a non-random distribution of HCV sequences in hepatic and extrahepatic compartments, 72,[87][88][89][90][91][92][93][94][95][96] leading to the conclusion that the presence of tissue-specific sequences is compatible with independent viral replication in extrahepatic sites. It has also been speculated that HCV variants within distinct compartments may differ in their sensitivity to interferon, although this hypothesis has not been formally tested.…”

Differences between hepatitis C virus 5' untranslated region quasispecies in serum and liver.

“…Comparison of PCR products amplified from such divergent and rapidly changing regions is technically challenging ; for example, as the template copy number in these studies was not adjusted and a relatively small number of clones was studied, part of the observed quasispecies heterogeneity could be artificial and represent sampling variations compounded by Taq polymerase and cloning errors. The results of two other studies, in which HCV quasispecies were compared by singlestrand conformation polymorphism (SSCP) analysis, contradict each other (Maggi et al, 1997 ;Sakamoto et al, 1995). Again, both studies were conducted on the E2 hypervariable region and the template copy number was not adjusted for individual reactions.…”

“…When compared with previous reports (Cabot et al, 1997 ;Maggi et al, 1997 ;Navas et al, 1998 ;Sakamoto et al, 1995 ;Shimizu et al, 1997), the present study has several unique features. Firstly, it was conducted on the most conserved part of the viral genome, which lowers the chance of artefactual polymorphism being detected.…”

“…Again, both studies were conducted on the E2 hypervariable region and the template copy number was not adjusted for individual reactions. Methodological differences and the lack of accounting for template copy number are also likely to be 0001-5872 # 1999 SGM HBB responsible for another incongruity of the published studies : while some authors have found liver quasispecies to be more complex than those derived from serum (Cabot et al, 1997), others have reported the opposite (Maggi et al, 1997 ;Navas et al, 1998). In addition, the replicating virus, as represented by HCV negative-strand RNA amplified with strand-specific assays, has not been analysed in any of the previous studies.…”